Stabilizer bars are a kind of torsion springs that keep a vehicle balanced by suppressing a roll motion of the car body. Accordingly, stabilizer bars are used as independent suspensions of vehicles to reduce inclination due to a centrifugal force when vehicles turn left or right or travel on a rough road. Mounting a stabilizer on a vehicle can improve riding comfort in traveling through a torsion angle.
Recently, actuators are used to control movement of a link or the center of a stabilizer. Actuators are mechanical parts that convert electric energy of an electric motor, a hydraulic motor, and an electromagnet etc. into a mechanical force.
However, when impact is applied to the inside of actuators due to rapid movement of wheels of a vehicle traveling on an abnormal road, it may have a bad influence on durability of the actuators. Accordingly, rubber bushes were inserted to attenuate impact in the related art, but durability of the rubber bushes is low and there is difficulty in performance tuning.
US Patent Application Publication No. 2010-0187778 discloses an electric active roll control apparatus. However, the apparatus uses a differential planetary gear and a multi-step planetary gear as power transmission units, so the left and right stabilizer bars are spaced by gear backlash in this structure.
Korean Patent Application Laid-Open No. 2011-0076832 discloses an actuator for a vehicle. However, although this actuator can adjust exhaust pressure by selectively opening/closing a waste gate valve, it cannot stably control the position of a vehicle.
On the other hand, the active stabilizer bars of the related art are composed of left and right stabilizers. Korean Patent Application Laid-Open No. 2008-0040058 discloses such a stabilizer. However, the active stabilizer bar has a problem in that coaxial precision is poor, when the co-axis between the left and right stabilizers or various gear assemblies are arranged.